CFD Analysis of Bed Textural Characteristics on TBR Behavior: Kinetics, Scaling-up, Multiscale Analysis and Wall Effects

Abstract

A simulation of a trickle bed reactor aided by computational fluid dynamics was implemented. With a Eulerian approach, geometrical characteristics were explicitly considered and two simultaneous heterogeneous reactions were included, hydrodesulphurization (HDS) and hydrodenitrogenation (HDN). This was performed in order to achieve the following: (1) attain further insight into a proper scaling‐up procedure to be able to obtain the same hydrodynamics and kinetics behavior in two reactors of different length and diameter scales; (2) develop a multiscale analysis regarding the communication of information between scales through the construction of a porous microstructure model from which the geometrical information of the microscale is captured by the effective transport coefficients (which affect the overall reactor behavior); (3) investigate the effect of operation conditions variations on hydrodynamics and kinetics; (4) and assess the deviations and further differences observed from average to punctual conversion values and the assumptions from kinetic literature models through a preliminary multiscale analysis. The CFD results were validated against experimental pressure drops data as well as HDS and HDN conversions theoretical data. An excellent agreement was found. The model produces a significant improvement in hydrodynamic parameters prediction, achieving 5 times better accuracy in predicting pressure drops and 50% improvement in holdup prediction. The fully coupled model predicts HDS conversion with 96% accuracy and HDN conversion with 94% accuracy. Results suggest that the best way to obtain similar kinetic and hydrodynamic behavior in TBRs with different length and diameter length scales is by equaling the liquid holdup (εγ) or the mass velocities (L‐G).